Padronização de ensaio imunoenzimático para diagnóstico da esporotricose

Abstract

Sporotrichosis is a fungal infection caused by traumatic inoculation in the skin with contaminated material with the dimorphic fungus Sporothrix schenckii. The most common clinical forms are fixed cutaneous and lymphocutaneous. Its prevalence is higher in the tropical and temperate zone. However, the actual prevalence of sporotrichosis in urban and rural areas is unknown because there is no mandatory reporting. The number of cases is increasing in the last years mainly due to transmission made by pets. The results of direct diagnostic methods take days to be released. In turn, serological methods may lead to false positive or negative results due to cross-reactions between antigens from S. schenckii with others fungi. Therefore, it is necessary to develop serological tests with high sensitivity and specificity to ensure a reliable diagnosis. This study aimed to standardize an enzyme immunoassay (ELISA) with higher sensitivity and specificity for serological diagnosis of sporotrichosis. In this work, polystyrene plates were sensitized with exoantigens obtained from yeast form of S. schenckii and tested using sera from patients with sporotrichosis, sera from patients with paracoccidioidomycosis (PCM), as well as individuals with sporotrichinin negative tests. Two strategies were used, one treating the antigen with sodium metaperiodate and another treating the serum with 6M urea at different incubation times. The results showed that the strategy using sodium metaperiodate not improved the discriminating power of the test sera from patients with sporotrichosis from those without sporotrichosis or with PCM. However, the strategy using 6M urea significantly improved discrimination power of the method. The best conditions of the test were the dilution of the sera to 1\800 and 1\1600 and treatment with urea for 5, 10 and 20 minutes.